Ch 1. LearningCurve: Numbers and Measurements

Select the correct answer for the following calculation. (7.63×10^−3) / (3.39×10^−6)

2.25×10^3 When dividing numbers in scientific notation, divide the coefficients and subtract the exponents of the powers of 10.

Evaluate the expression 2.57×10^−2 − 6.01×10^−1.

−5.75×10^−1 When subtracting numbers in scientific notation, the powers of 10 must have the same exponent. If the exponents are different, rewrite one number to use the other exponent, then perform the subtraction. Finally, check that the difference is written in correct scientific notation.

Reported to the correct number of significant figures, 0.025+0.750= _____.

0.775 When performing addition, the answer should be reported to the same number of decimal places as the least precise value. 0.025 and 0.750 are equally precise and have three decimal places.

Evaluate the expression 9.3×10^−4 + 1.4×10^−4.

1.07×10^−3 When adding numbers in scientific notation, the coefficients can be added together if the exponents are the same. Since 9.3×10−4+1.4×10−4=10.7×10−4, the sum must be rewritten in correct scientific notation as 1.07×10−3.

Convert 1.750 liters to milliliters.

1.750×10^3 mL To convert between liters, L, and milliliters, mL, use the relationship 1000 mL=1.0 L.

Reported to the correct number of significant figures, 1.0 ÷ 9.06 + 20.7 = _____.

20.8 In this calculation, division is performed first. When performing division, the answer should be reported to the same number of significant figures as the value with the least significant figures, in this case two. When performing addition, the answer should be reported to the same number of decimal places as the least precise value. The intermediate value from division has two decimal places and 20.7 has one decimal place, so the answer should be reported to the tenths place.

Reported to the correct number of significant figures, 10.45 / (15.98−12.9)= _____.

3.4 In this calculation, subtraction is in parentheses and therefore is performed first. When performing subtraction, the answer should be reported to the same number of decimal places as the least precise value. 3.08 is the result of this intermediate calculation, and it only has one significant digit after the decimal place. When performing division, the answer should be reported to the same number of significant figures as the value with the least significant figures. The intermediate from subtraction has two significant figures and 10.45 has four significant figures, so the answer should be reported to two significant figures.

Reported to the correct number of significant figures, 5.72−0.832= _____.

4.89 When performing subtraction, the answer should be reported to the same number of decimal places as the least precise value. The least precise value is 5.72 and has two decimal places.

Convert 915 K to degrees Celsius, ∘C.

642 ∘C The temperature in degrees Celsius, ∘C, is related to the temperature in kelvins, K, by the relationship TC=TK−273.15.

_____ refers to the closeness of recorded measurements to each other.

Precision